TISSUE MACROPHAGES ARE INFECTED BY HUMAN CYTOMEGALOVIRUS IN-VIVO

On the basis of in vitro experiments, it has been suggested that cells of hematopoietic origin play a major role in the pathogenesis and lat ency of human cytomegalovirus (HCMV), To elucidate the in vivo importa nce of hematopoietic cells in acute HCMV infection, tissue sections fr om various infected organs were investigated by immunohistochemical do uble-labeling analyses, Monoclonal antibodies directed against distinc t viral and cellular antigens were used to identify infected macrophag es, polymorphonuclear cells, and lymphocytes. Macrophages and polymorp honuclear cells were targets for HCMV infection in different tissues. Viral proteins representing all stages of permissive HCMV infection we re detected in macrophages, suggesting that these cells support the co mplete viral replication cycle. In polymorphonuclear cells, viral gene expression was restricted to the immediate early phase, indicating th at these cells are abortively infected, These findings suggest that ma crophages play an important role in the hematogenous spread of HCMV in to solid organs.